This invention relates to quick-connect couplings for hoses carrying compressed fluid. It is particularly adapted for use in hoses carrying compressed air to a tool or other equipment, although its usefulness is not limited thereto.
Compressed air hoses generally include a quick-connect coupling for connecting tools and the like. The coupling includes a female portion, also known as the coupler, connected to a source of compressed air, and a male portion, also known as the plug or nipple, generally attached to the equipment. Both the male and female portions include an axial bore through which the compressed air moves. When fully inserted, the free end of the plug engages and opens a spring-loaded valve in the coupler. The valve seats against a gasket when closed; when the valve is pushed open, air passages in a stem portion of the valve are moved to the upstream side of the gasket and permit air to flow through the coupling. The plug includes a circumferential indentation which is held by balls or pins in the coupler when the plug is fully inserted. The balls are held in a radially inward position by a spring-loaded sleeve, which is manually retracted to release the balls or pins, thereby permitting the plug to be released from the coupler.
A particularly effective coupling is described in Schneller, U.S. Pat. No. 2,279,146. Couplings made in accordance with this patent have been sold for many years by Lincoln Industrial Corp. of St. Louis, Mo., for example as its Model 815. Modern couplers made in accordance with this design may use pins rather than the balls 27, and the male portion (fitting F) is generally attached by a length of hose to the air chamber of a tool or other implement.
When the coupling is released, the coupler is of necessity being held by the person grasping the collar. The section of hose attached to the plug, however, is filled with compressed air and may whip about in a dangerous manner when released.
To prevent this problem, so-called safety couplings have been produced which permit a two-stage release of the plug and coupler. In the first stage, the plug moves sufficiently to permit air in its hose to be released; in the second stage, the plug itself is released. This type of system, however, is expensive to manufacture, is heavier than a standard coupling, and, because it requires two separate operations, is cumbersome and time-consuming to use. The problem of hose whip and the use of safety couplings to solve the problem are discussed, for example, by Richard T. Schneider in Hydraulics & Pneumatics, published Jul. 1, 2002, incorporated herein by reference.
Another approach is shown in Hiranuma et al., U.S. Pat. No. 5,582,204. That approach requires a specially formed coupler and a plug which is extremely difficult to manufacture. It also does not guarantee that the hose will not whip.
The patents referred to herein are incorporated herein by reference.